1. Field of the Invention
The present invention relates to a shoe adapted more particularly for the practice of a sport, the shoe being of the type that includes an upper and an external sole, as well as a lining, at least partially elastic, arranged inside of the upper.
2. Description of Background and Relevant Information
The use of such elastic linings, especially in sport shoes, is increasingly favored for the proprioceptive qualities which they provide.
For example, U.S. Pat. No. 2,147,197, filed in 1936, describes a sport shoe constituted of a jersey sock anchored through its end on the sole, and of an external upper partially surrounding the sock and fixed on the sole in a manner that is totally independent of the sock, the knitted structure of the sock providing the latter with a certain elasticity.
U.S. Pat. No. 4,736,531, filed in 1987, describes a sport shoe, adapted more particularly to aerobics, which includes a kind of internal half-sock completely surrounding the fore-foot, and whose end is anchored on the external sole, the sock being free to xe2x80x9cgripxe2x80x9d the foot independently of the external upper.
In this case, the sock is made out an extensible material such as that known under the commercial name Spandex, which, unlike U.S. Pat. No. 2,147,197, actually enables the sock to tightly envelop the foot and to follow the movements thereof.
Different constructions of sport shoes have likewise been proposed by French Patent Publication No. 2 711 896, such shoes being more particularly adapted for cross country skiing, and incorporating a lining made of an elastic material arranged inside an upper, in order to increase the sensations of the foot and of the ankle, and to locate, in an accurate manner, the respective space positions of such sensations that are indispensable to obtain a good precision of movement.
In fact, the type of shoe known from these two patent documents uses the proprioceptive qualities of certain parts of the foot and of the ankle.
To obtain an optimum response, it is necessary that the elastic lining tightly envelop the foot and the ankle by constituting a kind of second skin, regardless of the foot inserted inside the shoe.
Such an elastic lining must therefore be configured so as to define, at rest, a volume slightly less than the volume of the foot which it is adapted to receive, so as to exert a slight regular pressure thereon, without any excessive tightening.
In practice, these elastic linings are therefore designed with a volume slightly less than the volume of the narrowest foot that can be placed inside the shoe.
As a result, difficulties arise when putting on the shoe, especially for larger feet, these difficulties being more substantial as the elastic lining xe2x80x9crisesxe2x80x9d higher on the ankle as in the case of the sport shoes featured in French Patent Publication No. 2 711 896.
It has been provided in the above-identified French Patent Publication No. 2 711 896 to provide the elastic lining with a slit allowing for the positioning of the foot and being capable of being closed by self-gripping means.
However, such a construction does not allow for an accurate adjustment and adaptation of the volume of the sock or elastic lining to the volume of the foot.
Moreover, this construction with an opening slit is not compatible with the use of a high closed upper which only provides a very limited access to the inside of the shoe, such access being insufficient to easily open and close the slit of the lining.
One can also provide that the volume of the elastic lining correspond to that of an average foot to be place inside of the shoe. In this case, the problem of inserting large feet in the shoe remains, whereas a narrow foot no longer benefits from the tight enveloping of the elastic lining.
Finally, it is also advisable to be able to maintain a completely closed elastic lining structure, especially for reasons related to the imperviousness.
Therefore, an object of the invention is to overcome these disadvantages, and to provide a construction for a shoe with an improved elastic lining that reconciles the opposing problems related to an easy insertion of the foot, accurate adaptation to the volume thereof, and imperviousness.
An object of the present invention is also to improve the comfort aspects and proprioceptive sensations of such a shoe.
This object is achieved in the shoe according to the invention that is of the type constituted of an upper, an external sole, and a lining at least partially elastic arranged inside of the shoe, by the fact that the elastic lining defines, at rest, a volume that corresponds at least to that of the largest foot adapted to be received in the shoe, and that it includes means for adjusting its volume in view of an adaptation thereof to the real volume of the foot placed inside the shoe.
Such a construction makes it possible to maintain a completely close elastic lining, while allowing for an easy positioning of the foot due to the larger volume of this lining, and offering a possibility of accurate adaptation to each foot and, therefore, greater proprioceptive qualities.
According to an advantageous embodiment, the volume adjustment means are constituted by a double row of guides facing one another in a limited area of the elastic lining and spaced apart of/by a value corresponding substantially to the maximum difference in the volume of the foot, and by a loop through lace passing through the guides and associated with a traction and blocking means of this lace.
Thus, it suffices to exert a traction on the loop of the lace to bring the two rows of guides close together and to block this loop in the desired position in order to reduce the volume of the elastic lining to the desired value.
According to another aspect of the invention, the shoe is provided with a tongue that is elastically biased by the elastic lining against the user""s foot.
With such a construction, the tongue is pressed on the entire top portion of the foot, instep of the user, which makes it possible, on the one hand, to increase the area of the foot that is biased by the elastic lining and, therefore, to increase the proprioceptive sensations and information received by the foot and, on the other hand, to distribute, by means of the tongue serving as a pressure distribution plate, all of the elastic pressure exerted by the elastic lining over the entire portion of the foot being in contact with the tongue, i.e., both the top of the foot and the front tibial portion and, therefore, to obtain a more homogeneous and more comfortable distribution of pressure for the foot.
Such an embodiment is particularly interesting in the case of mountain or safety shoes provided with a relatively rigid external upper and equally relatively rigid tongue. Due to its relative rigidity, the tongue is entirely pressed on the corresponding portions of the foot and of the ankle.